Phenoxyphenylphosphinic acids and improved polyphenyl thioether lubricating compositions

ABSTRACT

PHENOXYPHENYLPHOSPHINIC ACIDS AND LUBRICATING COMPOSITIONS COMPRISIN OLYPHENYL THIOTHERS, POLYPHENYL ETHERS-THIOETHERS OR MIXTURES THEREOF AND SMALL AMOUNTS OF SAID ACIDS HAVE IMPROVED LUBIRCATING PROPERTIES OVER WIDE TEMPERATURE RANGES.

United States Patent PHENOXYPHENYLPHOSPHINIC ACIDS AND IM- PROVED POLYPHENYL THIOETHER LUBRI- CATING COMPOSITIONS Frank S. Clark, St. Louis, Mo., assignor to Monsanto Company, St. Louis, M0.

N0 Drawing. Original application May 28, 1971, Ser. No. 148,123. Divided and this application Oct. 6, 1972, Ser. No. 296,393

Int. Cl. C07f 9/48 US. Cl. 260-502.4 R Claims ABSTRACT OF THE DISCLOSURE Phenoxyphenylphosphinic acids and lubricating compositions comprising polyphenyl thioethers, polyphenyl ethers-thioethers or mixtures thereof and small amounts of said acids have improved lubricating properties over wide temperature ranges.

This is a division, of application Ser. No. 148,123, filed May 28, 1971, now US. Pat. 3,714,043.

This invention relates to phenoxyphenylphospinic acids and to improved lubricating compositions comprising polyphenyl thioethers, mixed polyphenyl ethers-thioethers and mixtures thereof, containing from 3 to 8 aromatic groups and a small amount of said phenoxyphenylphosphinic acid as a lubricating additive.

Polyphenyl thioethers and polyphenyl ether-thioether combinations have found wide application as functional fluids due to their excellent thermal stability and lubricity. For example they have been found to be valuable as hydraulic fluids and as lubricants in motor operation, particularly in jet engines.

Development of synthetic base stocks such as the polyphenyl thioether has provided lubricant fluids which are useful at elevated temperature such as 400 to 500 F. It is known that one of the aspects in which the polyphenyl thioether base stocks are considered deficient is in their lubricating characteristics. These lubricating characteristics include the load-carrying abilities and wear properties, especially under conditions of high pressures and temperatures reached in the advance design aircraft engines. Thus there is a demand for polyphenyl thioethers having improved lubricity properties.

An object of this invention is to provide novel phenoxy phenylphosphinic acids having excellent lubricating additive properties.

Another object of this invention is to provide improved lubricating compositions comprising polyphenyl thioethers, polyphenyl ether-thioethers, or mixtures thereof and a small amount of a phenoxyphenylphosphinic acid.

These and other objects will become evident upon consideration of the following specification and examples.

The phenoxyphenylphosphinicacids of this invention can be represented by the formula wherein R and R "are alkyl of not more than 4 carbon atoms, haloalkyl of not more than 4 carbon atoms and 3 halogen (Cl, Br and F) atoms, halogen (Cl, Br and F), hydroxyl or phenyl, and m and a are integers from 0 to 3.

Representative groups for R and R in the above formula include alkyl such as methyl, ethyl, ,propyl, isopropyl, n-butyl, sec-butyl and t-butyl and haloalkyl such as chloromethyl, bromomethyl, chloroethyl, bromoethyl,

trichloromethyl, tribromomethyl, dichloroethyl, chloro-npropyl, bromo-n-propyl, bromo-n-butyl, bromo-tert-butyl, 1,3,3-trichlorobutyl and 1,3,3-tribromobutyl.

Phenoxyphenylphosphinic acids represented by the above formula include, for example,

p-phenoxyphenylphosphinic acid, o-phenoxyphenylphosphinic acid, m-phenoxyphenylphosphim'c acid, p-(p-methylphenoxy)phenylphosphinic acid, o-(p-methylphenoxy)-p-methylphenylphosphinic acid, p-(o-methylphenoxy)phenylphosphinic acid, p-(p-ethylphenoxy)phenylphosphinic acid, p-(o-ethylphenoxy)phenylphosphinic acid, o-(o-ethylphenoxy)phenylphosphinic acid, p-(p-butylphenoxy)phenylphosphinic acid, p-(p-chlorophenoxy)phenylphosphinic acid, o-(m-chlorophenoxy)phenylphosphinic acid, p-(p-phenylphenoxy)phenylphosphinic acid, o-(p-phenylphenoxy)phenylphosphinic acid, p-(o-hydroxyphenoxy)phenylphosphinic acid, p-(m-bromophenoxy)phenylphosphinic acid, p-(p-hydroxyphenoxy)phenylphosphinic acid, o-(m-phenylphenoxy)phenylphosphinic acid, o-(p-methylphenoxy)-m-methylphenylphosphinic acid, o-(p rdnethylphenoxy)-m-ch1oromethylphenylphosphinic ac1 p-(p-methylphenoxy)-m-trifluoromethylphenylphosphinic acid, p-(o-butylphenoxy)-o trifluoromethylphenylphosphinic m-(o-phenylphenoxy)-p-methylphenylphosphinic acid, m-(o-methylphenoxy)-o-butylphenylphosphinic acid, m-(o ghloromethylphenoxy)-o-methylphenylphosphinic aci o-(m nethylphenoxy)-p-trifluoromethylphenylphosphinic ac1 o-(m-hydroxyphenoxy)-p-hydroxyphenylphosphinic acid, o-(m-phenylphenoxy)-m-chloromethylphenylphosphinic acid and p-(m-phenylphenoxy)-m-hydroxyphenylphosphinic acid.

the formula RY(R Y),,R

wherein R is phenyl, alkyl-substituted phenyl wherein the alkyl is of not more than 4 carbon atoms, alkoxy-substituted phenyl wherein the alkoxy is of no more than 4 carbon atoms or halogenated phenyl wherein the halogen is bromine, fluorine or chlorine, R is phenylene, alkyl or alkoxy-substituted phenylene where the alkyl contains no more than 4 carbon atoms or halogenated phenylene wherein the halogen is fluorine, bromine or chlorine, and Y is selected from oxygen and sulfur but at least one of the Ys is sulfur and n is an integer having a value of 1 to 6 and a lubricating additive amount of a phenoxyphenylphosphinic acid of the formula:

in amounts of from about 0.05 to 0.2% by weight based upon the total composition.

The polyphenyl thioethers employed in the composition of this invention have from 3 to 8 benzene rings and from 1 to 7 sulfur atoms with the sulfur atoms joining the benzene rings in chains as ether linkages.

By the term polyphenyl thioether as used herein is meant a compound or physical mixture of compounds wherein all of the Ys in the formula are sulfur. The term also includes those compounds which contain both oxygen and sulfur linkages between the benzene rings.

The compositions of this invention contain a major amount of the polyphenyl thioether base stock, i.e., at least 50% by weight of the total composition comprises a polyphenyl thioether. It is preferred that at least 60% by weight of the composition be a polyphenyl thioether base stock and even more preferred that at least 85% by weight of the total composition comprise a polyphenyl thioether.

Illustrations of the alkyl-substituents present in the phenyl and phenylene groups of the polyphenyl thioethers are for example, methyl, ethyl, propyl, butyl and the like. Illustrations of the alkoxy-substituents are, for example, methoxy, ethoxy, propoxy, butoxy and their isomers.

The composition of this invention can also contain from 0.01 to 10% by weight of the total composition of a dialkyl hydrogen phosphite extreme pressure additive. The dialkyl hydrogen phosphites useful are those wherein the alkyl groups contain from 1 to 12 carbon atoms. The alkyl groups are for example, methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, t-butyl, hexyl, decyl, isodecyl, dodecyl and the like.

Illustrative of the polyphenyl thioethers which can be employed as base stocks for the compositions of this invention are the bis(phenylmercapto)benzene. For example m-bis(pheny1mercapto) benzene o-bis (phenylmercapto) benzene p-bis (phenylmercapto) benzene bis (m-phenylmercaptophenyl) sulfide bis (o-phenylmercaptophenyl) sulfide bis (p-phenylmercaptophenyl) sulfide (m-phenylmercaptophenyl) (o-phenylmercaptophenyl) sulfide p-phenylmercapto-m'-phenylmercapto diphenyl sulfide o-bis (-phenylmercaptophenylmercapto) benzene p-bis (p-phenylmercaptophenylmercapto benzene p-bis (o-phenylmercaptophenylmercapto benzene p-bis (mphenylmercaptophenylmercapto )benzene m-bis (p-phenylmercaptophenylmercapto) benzene o-bis (p-phenylmercaptophenylmercapto benzene and the like and mixtures thereof.

Illustrative of the mixed polyphenyl ether-thioether compounds which can be employed as base stocks in the compositions of this invention are for example,

o-phenylmercapto-m-phenoxy benzene p-phenylmercapto-o-phenoxy benzene m-phenoxy-p-phenylmercapto benzene o-phenylmercapto-p'-phenoxydiphenyl sulfide o-phenylmercapto-m-phenoxydipheny1 sulfide o-phenoxy-m'-phenylmercaptodiphenyl sulfide m-phenoxy-p'-phenylmercaptodiphenyl sulfide o-phenoxy-p'-phenylmercaptodiphenyl sulfide p-phenoxy-p'-phenylmercaptodiphenyl sulfide o-phenoxy-o-phenylmercaptodiphenyl sulfide o,o'-bis (phenylmercapto) diphenyl ether o-phenylmercapto-m-phenylmercaptodiphenyl ether o-phenylmercapto-p-phenylmercaptodiphenyl ether m- (m-phenylmercaptophenylmercapto) (m-phenoxyphenylmercapto)benzene [m-(m-phenylmercaptophenylmercapto)phenyl] [m-(mphenoxyphenylmercapto)phenyl] sulfide 3- (m-phenylmercaptophenylmercapto) -3 (m-phenylmercaptophenoxy) diphenyl sulfide 3 ,3 khbis (m-phenylmercaptophenylmercapto) diphenyl e er 3-(m-phenylmercaptophenylmercapto)-3'-(m-phenoxyphenoxy) diphenyl sulfide 4- m-phenylmercaptophenylmercapto) -4'- (m-phenylmercaptophenoxy) diphenyl ether 3- (m-phenylmercaptophenylmercapto) -3 (m-phenoxyphenylmercapto)dipheny1 ether 4,4-bis (m-phenylmercaptophenoxy) diphenyl sulfide 4,4-bis (m-phenoxyphenylmercapto) diphenyl sulfide 3- m-phenoxyphenylmerc apto) -3 (m-phenylmercapto phenoxy) diphenyl sulfide 3,3'-bis(m-phenylmercaptophenoxy)diphenyl ether 4- (m-phenylmercaptophenylmercapto -4'- (m-phenoxyphenoxy)diphenyl ether 3- (p-phenylmercaptophenoxy) -3 (p-phenoxyphenoxy) diphenyl sulfide 3 (m-phenylmercaptophenoxy) -3 (m-phenoxyphenylmercapto)diphenyl ether 3,3'-bis(m-phenoxyphenylmercapto)diphenyl ether, and

3- (m-phenoxyphenylmercapto -3 (m-phenoxyphenoxy) diphenyl sulfide.

In addition to the foregoing compounds, the phenyl and phenylene of such compounds can contain substituents, such as alkyl of 1 to 4 carbon atoms, alkoxy of 1 to 4 carbon atoms and halogen such as chlorine, bromine and fluorine. Examples of such compounds are as follows: 4,4-bis(m-tolylmercapto)diphenyl ether 3,3'-bis(m-tolylmercapto)diphenyl ether 2,4-bis( m-to1ylmercapto)diphenyl ether 3,4'-bis (m-tolylmercapto)diphenyl ether 3,3-bis(p-tolylmercapto)diphenyl ether 3,3'-bis (xylylmercapto)diphenyl ether 4,4'-bis(xy1ylmercapto) diphenyl ether 3,4'-bis (xyly1mercapto)diphenyl ether 3,4'-bis(m-isopropylphenylmercapto)diphenyl ether 3,3-bis (m-isopropylphenylmercapto)diphenyl ether 2,4-bis(m-isopropylphenylmercapto)diphenyl ether 3,4'-bis(p-tert-butylpheny1mercapto)diphenyl ether 4,4'-bis (p-tert-butylphenylmercapto)diphenyl ether 3,3'-bis(p-tert-butylphenylmercapto)diphenyl ether 3,3-bis(2,4-di-tert-butylphenylmercapto)diphenyl ether 3,3'-bis(3-chlorophenylmercapto)diphenyl ether 4,4'-bis(3-chlorophenylmercapto)diphenyl ether 3,3-bis(m-trifluoromethylphenylmercapto)diphenyl ether 4,4'-bis (m-trifluoromethylphenylmercapto) diphenyl ether 3,4'-bis(m-trifluoromethylphenylmercapto)diphenyl ether 2,3'-bis(m-trifluoromethylphenylmercapto)diphenyl ether 3,3'-bis (p-trifluoromethylphenylmercatpo)diphenyl ether 3,3'-bis (o-trifluoromethylphenylmercapto)diphenyl ether 3,3'-bis (m-methoxyphenylmercapto) diphenyl ether 3,4'-bis(m-isopropoxyphenylmercapto)diphenyl ether 3,4-bis (m-perfluorobutylphenylmercapto)diphenyl ether 2-(m-tolyloxy-2'-phenylmercaptodiphenyl sulfide 2-(p-toly1oxy-3'-phenylmercaptodiphenyl sulfide 2-(o-tolyloxy)-4'-phenylmercaptodiphenyl sulfide 3-(m-tolyloxy)-3'-phenylmercaptodipheny1 sulfide 3-(m-tolyloxy)-4-phenylmercaptodiphenyl sulfide 4-(m-tolyloxy)-4-phenylmercaptodiphenyl sulfide 3-xylyloxy-4-phenylmercaptodiphenyl sulfide 3-xyly1oxy-3-phenylmercaptodiphenyl sulfide 3-phenoxy-3'-(m-tolylmercapto)diphenyl sulfide 3-phenoxy-4'- (m-tolylmercapto)diphenyl sulfide 2-phenoxy-3'- (p-tolylmercapto)diphenyl sulfide 3-phenoxy-4- (m isopropylphenylmercapto) diphenyl sulfide 3-phenoxy-3-(m-isopropylphenylmercapto)diphenyl sulfide 3mfioxy-Il'-(m-isopropylphenylmercapto)diphenyl su e 4-(rlnlggifluoromethylphenoxy)-4-phenylmercaptodiphenyl s e 3-(mlfiigiifluoromethylphenoxy)-4-phenylmercaptodiphenyl su e 2-(mlgaifluoromethylphenoxy)-3'-phenylmercaptodiphenyl su e 3- (m-trifluoromethylphenoxy) -3 -phenylmercaptodiphenyl sulfide 3- (p-chlorophenoxy) -3 -phenylmercaptodiphenyl sulfide 3- mrbromophenoxy) -4'-phenylmercaptodiphenyl sulfide bis- [m- (m-chlorophenoxy) phenyl] sulfide m-bis 3- (p-methyphenymercapto phenoxy benzene m-bis 3- (m-trifluoromethylphenoxy) phenylmercapto] benzene m-bis [3 (m-bromophenoxy) phenymercap to benzene 3, 3 '-bis [mp-methylphenylmercapto phenoxy] diphenyl sulfide 3 ,4'-bis [m- (p-methylphenylmercap to )phenoxy] diphenyl sulfide 3- (p-xenyloxy) -3 '-phenylmercapto diphenyl sulfide,

and the like and mixtures thereof. It is also contemplated within the scope of this invention to employ mixtures of polyphenyl ether-thioethers as base stocks.

The compositions of this invention are useful as lubricants under extreme conditions. The compositions are especially useful for steel on steel lubrication.

The phenoxyphenylphosphinic acids of this invention are prepared by interaction of a phosphine of the formula wherein R R m and a are as defined above with ethyl alcohol and water.

The interaction is carried out in the absence of a solvent by heating the admixture of the three components at temperatures up to and including reflux temperature. Pressure is not critical and subatmospheric, atmospheric and superatmospheric pressures can be employed. It is generally preferred to slowly add the phosphine to the ethyl alcohol and then to add the water to the admixture of phosphine and ethyl alcohol prior to heating. After reaction is complete, generally a period not exceeding more than or minutes, the excess ethyl alcohol and water are removed by azeotropic distillation with an azeotroping agent such as benzene.

The separation of the desired phosphinic acid from the azeotroping agent is readily accomplished by conventional means well known to the art. For example, distillation, fractional distillation under reduced pressure, selective extraction, fractional distillation using a carrier gas, film distillation, evaporation, elution, or any suitable combination of these methods.

Dichlorophenoxyphenylphosphines can be prepared by Friedel-Crafts condensation of diphenyl ethers with phosphorus trichloride in accordance with the procedure set forth in Organic Synthesis, 31, p. 88 (1951).

The following examples serve to further illustrate the invention. All parts are parts by weight unless otherwise expressly set forth.

EXAMPLE 1 This example describes the preparation of p-phenoxyphenylphosphinic acid. One part of dichloro-p-phenoxyphenylphosphine (B.P. 138-143 C./ 0.5 mm. Hg) is slowly added to five parts of absolute ethyl alcohol in a suitable vessel and then two parts of Water are added to the alcohol phosphine admixture with continuous stirring. The resulting admixture is heated at reflux for about five minutes. Evaporation of alcohol and water produces an oily substance. Residual alcohol and water are removed from the oily substance by azeotropic distillation using benzene as the azeotroping agent. The benzene is removed from the acid by evaporation producing an oil which slowly crystallizes. The crystals are dried and subjected to recrystallization from benzene and from an admixture of 70% benzene and 30% petroleum ether (B.P. 30-75 C.). The product p-phenoxyphenylphosphinic acid has a melting point of 96.5-98" C. and is confirmed by 6 EXAMPLE 2 A polyphenyl thioether-polyphenyl ether-thioether lubricant composition is prepared by combining p-phenoxyphenyl phosphinic acid (0.10 gram) with grams of a thioether of the following composition:

meta-bis(phenylmercapto)benzene (50% by weight) bis(m-phenoxyphenyl)sulfide (12.5% by weight) (m-phenoxyphenyl) (m phenylmercaptophenyl)sulfide (23.5% by weight) bis(m-phenylmercaptophenyl)sulfide (12.65% by weight) 3-ring and S-ring thioethers (1.35% by weight) and containing 10 parts per million of a dimethyl silicone antifoam agent (Dow-Corning-200, 350 cs. fluid). After stirring at 40 C. to dissolve the acid, the mixture is cooled to room temperature and filtered.

The resultant admixture was tested for lubricity with a slow speed four ball machine. A slow speed four ball machine measures the boundry lubricity action of additives. This test is a variation of the well known Shell Four Ball Test in which a ball is rotated against three stationary balls. Wear scars and/or seizure loads measure additive lubricity. In the slow speed instrument the three stationary balls are replaced with circular discs. Standard operating conditions are: 3 kg. load; 1 r.p.m.; and room temperature to 700 F.

The speed of rotation is very low, namely one r.p.m. This equals 0.88 inch/minute. This is done for two reasons. It insures boundary conditions, i.e., metal to metal contact. It also eliminates metal skin temperature flashes which can occur at high speeds. Thus the bulk oil temperature is equivalent to the metal surface temperature. Under these conditions wear is negligible and friction is used to follow lubrication. After covering the ball and disc with the test oil, the initial friction is recorded. The test sample is then heated at 700 F. with continuous recording of the friction. This gives a boundary frictiontemperature profile for the experimental fluid over this temperature range. The base stock was also tested for control purposes. When the mixture of Example 2 was tested by this procedure on M-5O tool steel, the observed coefiicient of friction was substantially lower than that for the base fluid over the temperature range from 340 to 700 F. Moreover a decrease in the coefiicient of friction began at 340 F. with the resultant admixture and not until 480 F. with the base stock.

The decrease in coefficient of friction indicates an improved performance in Falex tests for the compositions of this invention.

The embodiments of this invention in which an exclusive property or privilege is claimed are defined as follows:

1. Compound of the formula wherein R and R are alkyl of not more than 4 carbon atoms, haloalkyl of not more than 4 carbon atoms and 3 halogen atoms, halogen, hydroxyl or phenyl and m and a are integers from 0 to 3.

2. Compound of claim 1 wherein m and a are 0.

3. Compound of claim 1 wherein m is 1, a is 0 and R is alkyl.

4. Compound of claim 1 wherein m is 1, a is 0 and R is haloalkyl.

5. Compound of claim 1 wherein m is l, R is alkyl, a is 1 and R is alkyl.

6. Compound of claim 1 wherein m is 1, R is methyl, a is 1 and R is haloalkyl.

7. Compound of claim 3 wherein the alkyl is methyl.

8. Compound of claim 1 which is p-phenoxyphenylphosphinic acid.

7 9. Compound of claim 1 which is o-phenoxyphenylphosphinic acid.

10. Compound of claim 1 which is m-phenoxyphenylphosphinic acid.

References Cited UNITED STATES PATENTS 2,724,725 11/1955 Craig et al. 260-502.4R 2,727,067 12/1955 Craig et a1. 260502.4R 3,576,861 4/1971 Johns 260502.4R 10 8 OTHER REFERENCES 'Freedman et al., J. Org. Chem, vol. 35 (1960), pp.

140 to 142, Q0241J6.

J. E. EVANS, Assistant Examiner US. Cl. X.R.

260543 P, 612 R, 613 R 533 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 ,77 8 ,u72 Dated December 11, 1973 Inventor(s) Frank S. Clark It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

r- 7 Columns 1 and 2 line 58 of each column, the

formula which reads:

Signed and sealed this 9th day of April 197A.

(SEAL) Attest:

EDWARD I LFLE'ICHERQJR. C. MARSHALL DANN Commissioner of Patents Attesting- Officer 

